Paracyclophane-based ligands, their preparation and use in catalysis

Abstract

A substituted paracyclophane is described of formula (I) wherein X 1 and X 2 are linking groups comprising between 2 to 4 carbon atoms, Y 1 and Y 2 are selected from the group consisting of hydrogen, halide, oxygen, nitrogen, alkyl, cycloalkyl, aryl or heteroaryl and Z is a substituted or unsubstituted alkyl group, aryl group or heteroaryl group. Preferably X 1 and X 2 are —(C 2 H 4 )— and Z is a substituted aryl group. The substituted paracyclophane provides transition metal catalysts that are useful in C—C and C—N bond formation and asymmetric hydrogenation reactions.

The invention claimed is: 
     
       1. A substituted paracyclophane of formula (I) 
       
         
           
           
               
               
           
         
         wherein X 1  and X 2  are linking groups comprising between 2 to 4 carbon atoms, Y 1  and Y 2  are selected from the group consisting of hydrogen, halide, oxygen, nitrogen, alkyl, cycloalkyl, aryl and heteroaryl, and Z is an unsubstituted alkyl group, a substituted aryl group, an unsubstituted aryl group, a substituted heteroaryl group, or an unsubstituted heteroaryl group; 
         wherein when Z is a substituted aryl group, the substituents are selected from the group consisting of halide, hydroxyl alkoxy, carbonyl, carboxyl, anhydride, methacryl, epoxide, vinyl, nitrile, nitro, sulphate, sulphonyl, mercapto, amino, amine, imine, amide and imide. 
       
     
     
       2. The substituted paracyclophane according to  claim 1  wherein X 1  and X 2  are both —C 2 H 4 —. 
     
     
       3. The substituted paracyclophane according to  claim 1  wherein Z is a substituted or unsubstituted phenyl, naphthyl or anthracyl group. 
     
     
       4. The substituted paracyclophane according to  claim 1  wherein Z is a substituted aryl group having one or more substituting groups selected from the group consisting of halide, hydroxyl, alkoxy, carbonyl, carboxyl, anhydride, methacryl, epoxide, vinyl, nitrile, nitro, sulphate, sulphonyl, mercapto, amino, amine, imine, amide and imide. 
     
     
       5. The substituted paracyclophane according to  claim 1  wherein Z is a 2,5-disubstituted phenyl group. 
     
     
       6. The substituted paracyclophane according to  claim 2  wherein Z is a substituted phenyl, naphthyl or anthracyl group. 
     
     
       7. The substituted paracyclophane according to  claim 2  wherein Z is a substituted aryl group having one or more substituting groups selected from halide, hydroxyl, alkoxy, carbonyl, carboxyl, anhydride, methacryl, epoxide, vinyl, nitrile, nitro, sulphate, sulphonyl, mercapto, amino, amine, imine, amide and imide. 
     
     
       8. A method for preparation of a substituted paracyclophane of formula (I), comprising the steps of 
       
         
           
           
               
               
           
         
         (a) performing a substitution reaction on a pseudo-ortho dibromoparacyclophane to form an intermediate substituted bromoparacyclophane of formula (II), and 
       
       
         
           
           
               
               
           
         
         (b) reacting the substituted bromoparacyclophane with a phosphorus compound comprising P(Y 1 Y 2 ), wherein X 1  and X 2  are linking groups comprising between 2 to 4 carbon atoms, Y 1  and Y 2  are selected from the group consisting of hydrogen, halide, oxygen, nitrogen, alkyl, cycloalkyl, aryl and heteroaryl, and Z is an unsubstituted alkyl group, a substituted aryl group, an unsubstituted aryl group, a substituted heteroaryl group, or an unsubstituted heteroaryl group;
 wherein when Z is a substituted aryl group, the substituents are selected from the group consisting of halide, hydroxyl, alkoxy, carbonyl, carboxyl, anhydride, methacryl, epoxide, vinyl, nitrile, nitro, sulphate, sulphonyl, mercapto, amino, amine, imine, amide and imide. 
 
       
     
     
       9. The method according to  claim 8  wherein the substitution reaction is performed using a boronic acid, of formula Z—B(OH) 2 , in which Z may be substituted or unsubstituted. 
     
     
       10. The method according to  claim 9  wherein the boronic acid comprises a 2,5-disubstituted phenyl group. 
     
     
       11. A substituted bromoparacyclophane of formula (II) 
       
         
           
           
               
               
           
         
         wherein X 1  and X 2  are linking groups comprising between 2 to 4 carbon atoms, and Z is a substituted or unsubstituted alkyl group, aryl group or heteroaryl group; 
         wherein when Z is a substituted aryl group, Z is a 2,5-disubstituted phenyl group. 
       
     
     
       12. The substituted bromoparacyclophane according to  claim 11  wherein Z is a 2,5-disubstituted phenyl group.